Over the years, concerns have developed over the availability of conventional fuels (such as gasoline or diesel fuel) for internal combustion engine vehicles, the operating costs and fuel efficiencies of such vehicles, and the potentially adverse effects of vehicle emissions on the environment. Because of such concern, much emphasis has been placed on the development of alternatives to such conventional vehicle fuels. One area of such emphasis has been the development of vehicles fueled by natural gas or other methane-type gaseous fuels, either as the sole fuel or as one fuel in a dual-fuel system. As a result, vehicles using such fuels have been produced and are currently in use on a relatively limited basis both domestically and abroad.
Compressed natural gas is an abundant resource in the United States of America. It has been estimated that the known resources of natural gas are sufficient to supply the needs of the United States for at least 200 years.
In order to provide such gaseous fueled vehicles with a reasonable range of travel between refuelings, it has previously been necessary to store the on-board gaseous fuel at very high pressures, generally in the range of approximately 2000 psig (13.9 MPa) to 3000 psig (20.7 Mpa) or higher. Without such high-pressure on-board storage, the practical storage capacity of such vehicles was limited because of space and weight factors to the energy equivalent of approximately one to five gallons (3.7 to 19 liters) of conventional gasoline. Thus, by compressing the gaseous fuel to such high pressures, the on-board storage capacities of such vehicles were increased.
One disadvantage of the compressed gaseous fuel systems discussed above is that they require complex and comparatively expensive refueling apparatus in order to compress the fuel to such high pressures. Such refueling apparatus has therefore been found to effectively preclude refueling the vehicle from a user's residential natural gas supply system as being commercially impractical.
Another alternative to the above-discussed fuel storage and vehicle range problems, has been to store the on-board fuel in a liquid state generally at or near atmospheric pressure in order to allow sufficient quantities of fuel to be carried on board the vehicles to provide reasonable travel ranges between refuelings. Such liquified gas storage has also, however, been found to be disadvantageous because it requires inordinately complex and comparatively expensive cryogenic equipment, both on board the vehicle and in the refueling station, in order to establish and maintain the necessary low gas temperatures.
In the field of natural gas distribution and storage, there is a need to gather fuel (natural gas, methane, or hydrogen) from the existing pipeline distribution system. In the United States for a residential environment, natural gas suppliers typically deliver this gas at less than one psig. In order to carry enough natural gas fuel for a respectable driving range, the fuel must be compressed to at least 3,000 psig or 3,600 psig.
Many processes require the creation of extreme pressure changes. Many well known prior art inventions use multi-stage compressors or hydraulic rams to effect large volume changes on known gases. Because of the mechanical limitations of the standard piston and crankshaft designs, multi-stage compressors are often used when attempting to compress gasses from atmosphere to pressures over 500 psig. In one embodiment, by using a specially constructed sequencing valve, a simpler and more reliable single stage compressor can be used, resulting in increased reliability and significantly lower power consumption.
While a well lubricated piston and crankshaft is probably the most reliable and well understood means of compressing a gas, numerous other arrangements have been created to overcome its limitations.
While certain novel features of this invention shown and described below are pointed out in the annexed claims, the invention is not intended to be limited to the details specified, since a person of ordinary skill in the relevant art will understand that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation may be made without departing in any way from the spirit of the present invention. No feature of the invention is critical or essential unless it is expressly stated as being “critical” or “essential.”